This invention relates to an improved configuration of the inner tips of scroll wraps that facilitate opening of the discharge port to the compression chambers.
Scroll compressors are becoming widely utilized for many refrigerant compression applications. A scroll compressor consists of a fixed and an orbiting scroll each having interfitting wraps. The orbiting scroll moves relative to the fixed scroll to move compression chambers to a discharge port.
Much effort has gone into the design of the scroll wrap. Originally scroll wrap were configured as relatively thin wraps of a single thickness. More recently, thicker scroll wraps having a shape generally defined by alternate arcs of a circle have been developed. As shown in FIG. 1A, this type scroll compressor 10 includes an orbiting scroll wrap 11 and a fixed scroll wrap 12. The orbiting scroll wrap 11 is shown at a point immediately after completion of discharge. Orbiting scroll wrap 11 closes off the majority of the discharge port 13. As shown, the wraps 11 and 12 have an outer surface 14 that is essentially centered on a first radius R1 and a second surface 15 immediately following surface 14 which is centered on a second radius R2. Although only the fixed scroll wrap 12 is shown with the radii defined, the same configuration is preferably utilized to form the scroll wrap for the orbiting scroll 11.
In this prior art compressor, compression chambers 16 and 17 which are about to begin opening to the discharge port 13 are shown on each side of the connection between the inner tip of the wraps 11 and 12. The orbiting scroll 11 will move essentially in a direction X as the next increment of movement. Thus, the upper compression chamber 16 will immediately become open to the discharge port 13. The lower chamber 17, however, has a restriction 18 that will minimize the amount of fluid that can reach the discharge port 13 immediately. It would be desirable to have the chambers 16 and 17 communicate with the discharge port 13 in approximately equal amounts and time. Thus, the restriction 18 is undesirable. In addition, in the position shown in FIG. 1A, there is a small amount of fluid which is trapped between the wraps 11 and 12 at the end of the discharge cycle. That fluid becomes supercompressed, and can result in noise and forces tending to move the orbiting scroll 11 away from fixed scroll 12.
FIG. 1B shows an attempt to minimize the trapped fluid in the type of scroll compressor such as shown in FIG. 1A. As shown, the wrap 19 includes outer portion 14 and rear portion 15 centered on the radii R1 and R2. However, at an end point 21 of outer portion 14, a groove 22 is cut into the surface 15. This creates a chamber wherein the previously trapped fluid can be received such that the above-discussed problem does not occur. In this prior art scroll configuration, a line 23 extended from the surface 15 on the radius R2 would meet point 21. With this configuration, although the problem of trapped fluids may be reduced, the restriction 18 as illustrated in FIG. 1A still occurs. It is a goal of this invention to eliminate such restriction such that both compression chambers are quickly opened to the discharge port.